Abstract: Objective To identify mixed infection of Echinococcus granulosus and E.multilocularis in a dog from Xinjiang. Methods Thirty dogs from the pasture area were dissected and over 10 000 Echinococcus adult worms were found from one dog. Morphological observation revealed possible mixed infection of the two Echinococcus species. Further identification was made by amplification of the target gene DNA fragment (mitochondrial 12S rRNA gene). Results The adult worms of E.granulosus showed a relatively longer and larger gravid proglottid, its genital pore situated near or below the middle-side of the segment. The uterus was in a sacculate shape with irregular branches and approximately over 200-800 eggs in it. Morphology of the adult worms of E.multilocularis was similar to E.granulosus, slightly smaller, consisting of 4 to 5 proglottids. The uterus was not sacculate and with no branch. Its lateral genital pore often situated in the anterior part of the segment. Sequence analysis of mitochondrial 12S rRNA gene showed that amplification with the Eg1f/r primers shared complete identity with E.granulosus G1 genotype (GenBank accession no. AY462129), while that with the EmH15/17 primers shared complete identity with E.multilocularis (GenBank accession no. AB031351). The presence of both E.granulosus and E.multilocularis was confirmed by microscopy and gene identification. Conclusion Mixed infection of the two species of Echinococcus has been confirmed in the dog by morphological observation and PCR technique.

Key words: Echinococcus granulosus, Echinococcus multilocularis, Mixed infection, Dog, PCR identification